Fixing devices for being driven into and anchored in material

ABSTRACT

Fixing devices which can be hammered into and are self-anchoring in autoclaved aerated concrete and other like low density constructional material. Each device comprises a tubular shank with a head at the rear end and a longitudinal slit extending from the leading end of the shank, adapted for the two halftubular sections defined by the slit to be splayed apart by a pilot member and penetrate the material individually, and for the pilot member, part of which initially forms a bit at the front of the device, to punch a hole in the material. In two of these types a rear end of the pilot member is acted on directly by a punch through a passage in the shank, so that the rear end of the pilot member will remain in the shank forward of the shank head. In another two of these types an annular retainer initially encircles the two half-tubular sections to hold them together. After the annular retainer abuts the material, further penetration by the shank of the material moves the retainer along the shank and allows the splaying apart of the two sections. Upon splaying apart, in each device the half-tubular sections grip the pilot member bit between their edges so that the bit maintains the sections splayed apart to positively lock the shank in the material.

United States Patent Lunn et a1.

FIXING DEVICES FOR BEING DRIVEN INTO AND ANCHORED IN MATERIAL [75] Inventors: Peter Louis Lunn, Hartford; Alan Roy Peters, Sevenoaks, both of England; George Samuel Webster, Rhyl, Wales [73] Assignee: Lun web (Products) Limited,

Aylesbury, England [22] Filed: Nov. 12, 1973 [2]] Appl. No.: 414,650

Related US. Application Data [63] Continuation-in-part of Ser. No. 217,578, Jan. 13,

1973, abandoned.

[30] Foreign Application Priority Data June 14, 1971 United Kingdom 27780/71 Sept. 16, 1971 United Kingdom 43274/71 52 us. Cl. 85/26; 85/68; 85/77 [51] Int. Cl. F16B 15/04 [58] Field of Search 85/68, 85, 26, 23, 67, 85/77 [56] References Cited UNITED STATES PATENTS 1,165,778 12/1915 Howard 85/23 2,089,578 8/1937 Schaefer 85/85 2,150,788 3/1939 Shippee et a1. 85/26 2,171,985 9/1939 Mushet 85/68 2,283,243 5/1942 Vatet 85/26 FOREIGN PATENTS OR APPLICATIONS 468,206 12/1951 Italy "S 85/26 1,326,065 3/1963 France 85/68 Primary Examiner-Edward C. Allen Attorney, Agent, or Firm-Prutzman, Hayes, Kalb & Chilton [57] ABSTRACT Fixing devices which can be hammered into and are self-anchoring in autoclaved aerated concrete and other like low density constructional material. Each device comprises a tubular shank with a head at the rear end and a longitudinal slit extending from the leading end of theshank, adapted for the two halftubular sections defined by the slit to be splayed apart by a pilot member and penetrate the material individually, and for the pilot member, part of which initially forms a bit at the front of the device, to punch a hole in the material. In two of these types a rear end of the pilot member is acted on directly by a punch through a passage in the shank, so that the rear end of the pilot member will remain in the shank forward of the shank head. In another two of these types an annular retainer initially encircles the two half-tubular sections to hold them together. After the annular retainer abuts the material, further penetration by the shank of the material moves the retainer along the shank and allows the splaying apart of the two sections. Upon splaying apart, in each device the half-tubular sections grip the pilot member bit between their edges so that the bit maintains the sections splayed apart to positively lock the shank in the material.

5 Claims, 14 Drawing Figures US Patent Sept. 23,1975 Sheet 2 of 3 3,906,832

FIXING DEVICES FOR BEING DRIVEN INTO AND ANCHORED IN MATERIAL This is a continuation-in-part of our US. Pat. application Ser. No. 217,578, filed Jan. 13, 1972 and now abandoned.

This invention relates to fixing devices for being driven into and self-anchoring in autoclaved aerated concrete and other like low density constructional material.

BACKGROUND OF THE INVENTION Autoclaved aerated concrete and other like low density constructional materials have characteristics of limited compressive strength, limited tensile strength, ready compactibility (usually because of being cellular) to form a cavity for a fixing device, and substantially no recoverability or resilience. These characteristics in combination render very many fixing devices which are good or even excellent in other materials virtually useless in autoclaved aerated concrete and other like low density constructional materials. For example, an ordinary nail can be hammered straight into autoclaved aerated concrete without any need for a predrilled hole, but the nail can be pulled straight out again by the unaided hand.

Devices such as those known as Rawlplugs" have long been available for fastening screws to brickwork by the method of drilling a passage in the brickwork, inserting a Rawlplug" in the passage and screwing the screw into the Rawlplug so as to expand the Rawlplug" into engagement with the sides of the passage. Rawlplugs themselves are fibrous. Equivalent alternative devices of molded plastics are also known.

The need to drill a passage in brickwork for a Rawlplug" arises from the high compressive strength and non-compactibility of brickwork, requiring the drilling to remove brick material to form the passage. However, the characteristics of high compressive strength and non-compactibility make the eventual Rawlplug fixture in brickwork very strong.

When using a Rawlplug" in brickwork, it is necessary to drill the passage of just the right diameter and just the right length, neither too wide, nor too narrow, nor too long, nor too short.

None of these devices is particularly satisfactory, however, if used in autoclaved aerated concrete or other like low density constructional material, owing to the readiness of the cell walls to collapse nonrecoverably and hence loosen the devices.

US. Pat. No. 2,283,243 (Vatet) discloses two fastening devices for holding an outer sheathing such as clapboard or wall shingles or the like to a comparatively soft fibrous or granular inner sheathing of comparatively little thickness. such as fiber, plaster, or gypsum board, in low cost housing projects. Each fastening device consists of a head. and a shank. the outer portion of which is of sufficient length and strength to withstand hammer blows and extend through the outer sheathing and the inner portion of which is perforated axially to form a series of weaker portions which suecessively break and permit the bevelled points to spread the inner portion of the shank out into the inner sheathing as it is being driven, the metal surrounding the perforations forming barbs which bite into the structure of the inner sheathing and hold the fastening device firmly in place without passing through the inner sheathing.

The first of the two Vatet fastening devices has a series of holes formed along the inner portion of the shank, i.e. near the point which is provided with an interior bevel, viz tapered downwardly and outwardly, there remaining between the holes small sections of metal which give rigidity to the inner portion of the shank, preventing appreciable spreading of the shank until after it passes through the outer sheathing.

When this first fastening device is fully driven the bevelled points cause the sections of the shank to diverge on arcuate paths, the severed metal sections forming barbs firmly embedded in the material of the inner sheathing, thus obtaining a firm anchorage for the head to retain the outer sheathing in intimate contact with the inner sheathing.

The second Vatet fastening device employs the same principles as the first. However, the second Vatet device is modified in that it has .a tubular shank with the perforations arranged to produce four lines of weakness and in that a wedge is inserted between the bevelled edges of the prongs. This wedge has a point which centers the wedge and maintains, in conjunction with a cylindrical portion lying within the tubular shank of the fastening device, a short straight path of penetration of the wedge into the inner sheathing. In this case a sloping surface of the wedge starts and insures the equal severance of the thin :metallic portions which until they pass through the outer sheathing prevent the buckling of the segments of the shank.

In the second Vatet device there are also barbs which are pressedinto the material of the inner sheathing and together with the other barbs insure that the anchorage is even greater than that due to the additional number of prongs.

Neither of the two Vatet devices could be used successfully as a fixing device in autoclaved aerated concrete.

One reason for this is that the barbs rely to a great extent upon resilience in the sheathing and would be ineffective in autoclaved aerated concrete, which would crumble with the insertion of the barbs, with no recovery, and which could not withstand the high concentrations of stress produced by the barbs. Thus each device could be easily pulled out.

The wedge of the second Vatet device could not be driven into autoclaved aerated concrete by hammer blows upon the head of the shank, because the sections of metal would sever between the holes before the wedge had penetrated to an appreciable depth. Furthermore, there would be no gripping of the wedge between the spread-apart sections of the shank to prevent the spread-apart shank sections coming together and permitting the shank to be pulled out of the concrete.

Of course, both Vatet devices are designed not at all for use in autoclaved aerated concrete but for entirely different types of material.

US. Pat. No. l, 165,778 (Howard) discloses a railroad -spike constructed so that after it has been driven into a tie. a locking sleeve mounted upon a body portion of the spike may be driven inwardly to cause points at the inner end of the sleeve to be spread and thus prevent the spike from working loose. The sleeve and body portion of the spike is constructed so that when first driven into the tie, the sleeve and body portion of the spike will travel along and not cause the points of the sleeve to spread until the spike is in engagement with the rail base.

A rail after being placed upon the tie is held in place by a number of the spikes which are driven into the tie and then locked. Each spike is provided with a rail base-engaging head which engages the rail base and with a spreading head which terminates in a penetrating point. The spreading head has two of its faces extending in diverging relation to cause the prongs of the locking sleeve to spread and has its remaining faces extending flush with the side faces of the spike.

The sleeve which is slidably mounted upon the spike has its side walls terminating short of the lower ends of the front and rear walls and separate from the front and rear walls for a short distance so that tongues will be formed. The tongues which form the locking spurs have their inner faces bevelled so that these inner faces will fit flatly against sloping shoulders of the spreading head. An upper edge portion of the front wall is cut at an incline to permit the spike to be driven into the tie very close to the rail base and also to permit the wood of the tie to close in around the upper edge portion of the sleeve after the sleeve has been driven to a locked position and assist in holding the spike in place. The rear wall extends above the side walls and is provided with a heel which permits the sleeve to be easily driven into the locked position.

When this spike is in use, the spike is driven into the tie with the sleeve in the raised position until the spike has been driven into the tie a sufficient distance to bring the rail base-engaging head into engagement with the rail base. The heel is now struck with the hammer and the sleeve will be driven downwardly thus causing the prongs to be spread by the sloping shoulders of the spreading head.

If the Howard spike were used or attempted to be used in autoclaved aerated concrete, which is more crumbly and less dense than the wood ofa railroad tie, it would be found that the sleeve would work loose because the face-to-face contact between the prongs and the sloping shoulders of the spreading head would not provide a slip-free or non-sliding grip of the spreading head and the prongs, in the absence of gripping of the spreading head by the prongs at highly concentrated localised stress areas between the prongs and the spreading head.

Furthermore, the anchoring of the Howard spike by means of the sleeve prongs is indirect, relying on faceto-face contact between respective surfaces of the spike and the sleeve, particularly the surfaces of the spreading head of the spike and the prongs of the sleeve, rendering the device most unsuitable for use in a crumbly, low density building material like autoclaved aerated concrete.

SUMMARY OF THE INVENTION Broadly speaking, the invention provides fixing devices for being driven into and self-anchoring in autoclaved aerated concrete and like low density constructional material without requiring a preformed opening to penetrate the material, the fixing device comprising a shank, a rear end of the shank forming a head whereby the shank can be driven into the material, the remainder of the shank being formed as a tube with an axial passage therein forming an opening at a leading end of the shank, a pilot member received in the shank passage and having a bit which prior to use is in front of said end opening and wider than the passage in the shank, the pilot member bit being constructed and configured relative to said end opening to penetrate the material to a predetermined depth with the pilot member bit forming a passage in the material for the undeformed shank, the leading end portion of the shank being split rearwardly from its end opening into longitudinally extending part-tubular sections having sufficient resistance to longitudinal loading to allow following movement of the shank in unison with the pilot member bit through the passage so formed in the material without appreciable divergence of the split leading end portion of the shank upon driving the shank and the pilot member as a unit to said predetermined depth, said pilot member being engageable with the parttubular sections formed by the split leading end portion of the shank to progressively splay the part-tubular sections apart so that they outwardly diverge to anchor the shank in the material as the shank is thereafter driven further into the material with the pilot member disposed at said predetermined depth and with the rear end of the pilot member disposed in the shank passage forwardly of the shank head, edges of the part'tubular sections being engageable with the pilot member at angularly spaced apart places on the pilot member to exert a gripping action upon the bit with localised areas of pressure and friction, to prevent subsequent withdrawals of the shank relative to the pilot member when the pilot member has splayed the part-tubular sections apart upon said further driving of the shank into the material, whereby the pilot member maintains the parttubular sections splayed apart to anchor the shank positively in the material.

IN THE DRAWINGS FIGS. 1 to 3 show successive stages in the driving into and anchoring in autoclaved aerated concrete or other like low density constructional material of one fixing device in accordance with the invention, to fix a wooden member to the said constructional material;

FIG. 3a is a section on line IIIA-IIIA of FIG. 3;

FIGS. 4 and 5 illustrate another fixing device in accordance with the invention, FIG. 4 showing the device by itself, prior to use, and FIG. 5 showing the device self-anchored in low density constructional material after being driven through softwood and into the constructional material to fix the softwood to the material;

FIG. 5a is a section on line VAVA of FIG. 5;

FIGS. 6 and 7 illustrate another fixing device in accordance with the invention, FIG. 6 showing the device by itself, prior to use, and FIG. 7 showing the device self-anchored in low density constructional material after having been driven through softwood into the constructional material, fixing the softwood to the material;

FIG. 7a is a section on line VIIaVIIa of FIG. 7;

FIGS. 8, 9 and 10 show successive stages in the driving of another fixing device in accordance with the invention through softwood and into low density constructional material to become self-anchored in the constructional material, fixing the softwood thereto; and

FIG. 10a is a section on line XAXA of FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fixing device illustrated in FIGS. 1 to 3 and 3a comprises a tubular shank 1, a rear end of the shank l forming an enlarged head 2. A leading end portion 3 of the shank 1 is split or divided longitudinally into two half-tubular sections 4 and 5 which can splay apart so as to anchor the shank 1 in material.

The device is shown being driven through a softwood member 6A and into autoclaved aerated concrete or like low density constructional material 6B to become self-anchored in the material 6B and hence secure member 6A to material 68.

The device of FIGS. 1 to 3 further comprises a pilot member 7 adapted and arranged to be driven through the member 6A and into the material 68 with a front part 8, forming a bit, of the pilot member 7 initially ahead of the front end 9 of the shank 1 prior to splaying apart of the shank sections 4 and 5. The fixing device of FIGS. 1 to 3 is constructed so that, as shown in FIG. 3, the shank 1 can be driven further into the material 68 with the shank sections 4 and 5 splaying apart over the bit 8 of the pilot member 7.

More particularly, the shank 1 has a through-passage 10 therein extending from end-to-end of the shank 1, the passage 10 having openings 11 and 12 at both ends 9 and 2 of shank l. The bit 8 of pilot member 7 is wider than the leading end passage opening 11; indeed, it is the same diameter as the outside diameter of the leading end 9 of the shank 1, prior to splaying apart of the shank sections 4 and 5. The pilot member 7 comprises an elongate stem portion 14 extending rearwardly of the bit 8, the pilot member 7 being of a shorter length than the shank l. A rear end 15 of the elongate stem portion 14 lies forwardly of the rear end tool-receiving passage opening 12 at least prior to splaying apart of shank sections 4 and 5. The pilot member 7 is capable of being driven through the softwood 6A and into the material 6B by means of action of a tool punch 16 (inserted through the rear end passage opening 12) upon the rear end 15 of the elongate portion 14 of the pilot member 7 as shown in FIGS. 1 and 2. Thereafter, the head 2 of shank 1 can be acted upon directly to drive the shank 1 into the material 63 so that the shank sections 4 and 5 splay apart over the bit 8 with the rear end 15 of the pilot member stem 14 shown as being in the shank passage 10 forward of the shank head 2 (FIG. 3) after the assembly has been driven into the material 63, so as to be normally inaccessible and unable to be disturbed to loosen the grip of shank sections 4 and 5 upon the pilot member bit 8.

The rear end 17 of the bit 8 tapers rearwardly, whilst the passage opening 11 is flared.

The tool punch 16 is in fact a spigot projecting for- -wardly of a tool body portion 18 having a flange 19 which extends forwardly of a surface 20 engaging the shank head 2. The length of the spigot is such that when an upper end (not shown) of the tool body portion 18 is struck by a hammer, not shown, both the shank 1 and the pilot member 7 are driven directly into the material 68 with the relative positions shown in FIGS. 1 and 2 maintained until the stage shown in FIG. 2 is reached. At this stage the tool is removed and the shank head 2 is struck a number of blows, driving the shank 1 into the material 6B to the position shown in FIG. 3 with little or no further advancement of the pilot member 7 into the material 68.

It will be appreciated that the device shown in FIGS. 1 to 3 is adapted to form a passage for itself in the material and that the shank parts 4 and 5 are adapted to pen etrate into the material 6B individually upon splaying outwardly.

The taper 17 and flared leading end passage opening 11 co-operate to cause the shank sections 4 and 5 to be splayed apart as they are driven further into the material 68 until finally the position shown in FIG. 3 is reached.

As shown in FIG. 3a, the bit 8 is gripped by the edges 4a and 5a of the half-tubular shank sections 4 and 5. Since the section edges are relatively thin, the areas of contact are localised so that the pressure and friction are very high. This prevents the bit 8 from slipping out from between shank sections 41 and 5 in the event that an attempt is made to pull the shank 1 out of the material 6B. Instead, the bit 8 remains gripped by and between shank sections 4 and 5, maintaining sections 4 and 5 splayed apart and hence positively and securely anchored in the material 6B.

In this position the device is firmly anchored in the autoclaved aerated concrete 6B. A

The front end of the bit 8 should be sufficiently sharp to penetrate the softwood 6A and the low density constructional material 6B when the tool is being used, but sufficiently blunt to present sufficient resistance to movement when the head 2 is being struck, i.e. after the position shown in FIG. 2 has been reached.

Although the leading end portion 3 of the shank 1 has baen shown divided into two half-tubular sections 4 and 5, it will be appreciated that they may be divided into more than two part-tubular sections if so desired.

Although the device may normally be manufactured from iron or steel, it will be understood that, for special applications, the device may be manufactured from other materials, such as plastics.

If desired, the embodiment described above may be modified to provide an anchorage for a nut or bolt. In the former case, the device includes a post having an external screwthread which is left upstanding above the surface of the softwood 6A after the device has been fully inserted in the material, a suitable tool being provided for inserting the device. In the latter case, the device is provided with an internally threaded bore for receiving the bolt. In both cases, the device may be of a two-piece construction similar to that shown in FIGS. 1 to 3.

The fixing device shown in FIGS. 4, 5 and 5a comprises a tubular shank 25, a rear end of the shank 25 forming an enlarged head 26. A. leading end portion 28 of the shank 25 is split or divided longitudinally into two half-tubular sections 29 and 30 which can splay apart, from the positions shown in FIG. 4 to the positions shown in FIG. 5, so as to anchor the shank 25 in low density constructional material 278, (autoclaved aerated concrete).

The device shown in FIGS. 4 and 5 further comprises a pilot member 31 adapted and arranged to be driven through softwood 27A and into the low density constructional material 27B. A forward part of the pilot member 31 forms a bit 32 which is integral with a rear end part 40, parts 32 and 40 both being initially ahead of the leading end 33 of the shank 25, as shown in FIG. 4, prior to splaying apart of the shank sections 29 and 30. The fixing device of FIGS. 4 and 5 also is constructed so that the shank 25 can be driven further into the material 278 to the position shown in FIG. 5, with shank sections 29 and 30 splaying apart over the pilot member 31 as shown in FIG. 5, to fix the softwood 27A to the low density constructional material 278.

The device shown in FIGS. 4 and 5 further comprise. an annular retainer in the form of a sleeve 34 initially encircling the leading end portion 28 of shank 25, be hind the bit 32, to restrain shank sections 29 and 36 from splaying outwardly. The end of the sleeve 34 has a flange 35 which abuts a surface 36 of the softwood 27A as shown in FIG. 5 before the shank itself has been driven into the material 278 to the position shown in FIG. 5 so that driving in of the shank 25 to that position moves the sleeve 34 relatively rearwardly along the shank 25, thereby permitting the splaying apart of shank sections 29 and 30.

It will be appreciated that the device shown in FIGS. 4 and 5 is adapted to form a passage for itself in both the softwood 27A and the low density constructional material 27B and that the shank sections 29 and 30 are adapted to penetrate individually into the material 278 upon splaying outwardly.

The similarity of FIG. 5a to FIG. 3a will be immediately apparent. The edges 29a and 30a of shank sections 29and 30 grip the pilot member 31 with localised areas of high pressure and friction contact, so that the shank 25 cannot be withdrawn to leave the pilot member 31 behind.

The sleeve 34 may be replaced by a washer or collar, not shown.

The shank 25 which is of circular cross-section has, formed in a leading end portion 28 thereof, a slit 37 which divides said portion 28 into the two half-tubular sections 29 and 30. The end of said leading end portion 28 is formed with a countersink.

The sleeve 34, which is formed by a thin walled tube, surrounds the slit leading end portion of the shank 25 and projects rearwardly of the slit 37. The flange of sleeve 34 engages a circumferential rib 39 formed on the shank 25 so that the shank is normally prevented from moving axially through the sleeve.

The pilot member 31 is bullet shaped and pointed at both ends. The rear end part 40 of the pilot member 31 is reduced in diameter and is a friction fit in the open end of the sleeve 34 so that the rear end part 40 of pilot member 31 is normally held therein, the point of said rear end part 40 being located in the countersink in the leading end 33 of the shank 25. The bit-forming leading end part 32 of the pilot member 31 is disposed outside the sleeve 34 and its point facilitates penetration of the softwood 27A and low density constructional material 278 when the device is driven thereinto.

When the device shown in FIGS. 4 and 5 is driven through the softwood 27A and into the material 278 by striking the head 26 of the shank 25, the pilot member 31 and the sleeve 34 penetrate the softwood 27A and the material 278 until the flange 35 of the sleeve 34 comes into contact with the surface of the softwood 27A. The sleeve 34 is therefore held against further movement so that, on further striking of the head 26 of the shank 25, the latter is driven through the sleeve 34, the impact causing the rib 39 on the shank 25 to be deformed by the sleeve 34 so as to allow the shank 25 to pass through the latter. The pilot member 31 is also pushed out of the open end of the sleeve 34 by the shank 25, the frictional engagement of the pilot member 31 in the sleeve 34 being overcome, but the pilot member 31 is then prevented from penetrating further into the material 278 by the resistance of the latter. As

the shank sections 29 and 30 emerge from the front end of the sleeve 34 they are splayed apart by the pilot member bit 32 so that, when the shank 25 is driven fully home as shown in FIG. 5, shank sections 29 and 30 firmly anchor the device in the material 278, gripping the bit 32 between them, to fix the softwood 27A to the material 278.

The device shown in FIGS. 4 and 5 can be inserted into and anchored in the material 278 in two stages. In the first stage, a tool (not shown) may be used to punch a hole through the softwood 27A and into the material 27B, (autoclaved aerated concrete being compactible because of the aeration, softwood also being compactible,) to a depth such that, when the device is inserted pilot member-first into the hole until the flange 35 of the sleeve 34 contacts the surface of the softwood 27A, the pilot member 31 is in contact with or at least very close to the bottom of the hole. Preferably, however, no tool is used and, in the first stage, the device is partially driven, for example by hammer blows, through the softwood 27A and into the material 278 until the flange 35 contacts the surface of the softwood 27A. In this first stage the shank 25, sleeve 34 and pilot member 31 move together. In the second stage the shank 25 is driven further into the material 27B; the shank 25 first pushes the pilot member 31 out of the front end of the sleeve 34, whereupon the resistance of the material 27B prevents further movement of the pilot member 31, and then the bit 32 splays apart the shank sections 29 and 30 of the shank 25. If the shank 25 is driven through the softwood 27A and into the material 273 without using a tool to initially form a hole, both first and second stages can be performed in a single continuous operation and it is to be noted that there is some advantage in not having to provide a special tool for this purpose. When the device is finally anchored in position the pilot member 31 is disposed at the junction of the splayed-apart sections 29 and 30, and is gripped between the side edges 29a and 30a of the half-tubular sections 29 and 30 as shown in FIG. 5a with localised areas of high pressure and friction contact.

The fixing device illustrated in FIGS. 6, 7 and comprises a shank 41, a rear end 42 of the shank 41 forming an enlarged head whereby the shank 41 can be driven into low density constructional material, (not shown,) such as autoclaved aerated concrete, for example Thermalite, and a front end portion 43, (i.e. the whole of the shank 31 except the rear end 42,) of the shank 41 being tubular and split or divided longitudinally into two sections 44 and 45 which splay progressively further apart so as to anchor the shank 41 in the material as the shank 41 is driven into the material.

The fixing device illustrated in FIGS. 6, 7 and 7a further comprises a member in the form of a pilot member 46 adapted and arranged to be driven into low density constructional material (not shown) with all of the pilot member 46 except a rearend stub 47 forming a bit 49 located initially ahead of the front end 48 of the shank 41, as shown in FIG. 6, prior to splaying apart of the shank sections 44 and 45. The fixing device of FIGS. 6, 7 and 7a also is constructed so that the shank 41 can be driven further into the material with the shank sections 44 and 45 splaying apart over the pilot member 46, in particular over the bit-forming front part 49, (i.e. all except rearward end part 47,) of the pilot member 46 initially ahead of the shank front end 48.

The fixing device illustrated in FIGS. 6, 7 and 7a fur ther comprises an annular retainer member 50 in the form of a washer initially encircling the front end portion 43 of a shank 40 to restrain the shank sections 44 and 45 from splaying outwardly, as shown in FIG. 6. The washer 50 is movable relatively rearwardly along the shank 41 by engagement with the surface of the material (or with the surface of softwood not shown being fixed by means of the device to the material) as the shank 41 is driven into the material, thereby permitting the splaying apart of the shank sections 44 and 45, which individually penetrate into the material upon splaying outwardly.

The stub 47 extends rearwardly of the bit 49 of the pilot member 46 and between said sections 44 and 45 of the shank 41, said sections 44 and 45 initially gripping the stub 47 and hence holding the bit 49 ahead of the front end 48 of the shank 41 until said outward splaying of sections 44 and 45 has commenced. The stub 47 may or may not be narrower than the bit 49 and the stub 47 may or may not be faired into the bit 49 smoothly. The front end of the bit 49 is preferably pointed. To withstand being driven into the material, the pilot member 46 is preferably solid rather than hollow.

The shank 41 may be rolled from strip material, or half rolled (into a semi-circular cross-section) and then folded in two, or machined from a sleeve. The head 42 may be shaped like the head of a nail or simply be the rear end of the shank 41 without any special formation apart from being able to be acted upon as aforesaid, preferably by a hammer.

The shank 42 and bit 46 are of steel, whilst the washer 50 is of brass or steel.

The formation of the shank 41, from strip material, includes the steps of half rolling the strip material, (into a semi-circular cross-section), then folding the strip material into two, so as to form a circular cross-section divided by a slit into two semi-circular cross-sections, (the cross-sections of the sections 44 and 45 respectively,) and then forming the head 42, which is shaped like the head of a nail.

It will be apparent that a collar or sleeve, not shown, may be used in place of the washer 50 as an annular retainer. The pilot member 46 may be somewhat smaller than shown, and the stub 47 somewhat longer, to maintain the pilot member 46 in alignment with the shank 41. Instead of being half rolled and then folded, the shank 41 may be rolled from a wider strip into a circular cross-section with one slit along its whole length, and a leading end portion of the shank 41 further slit longitudinally into two or more sections (either before or after rolling). I

The fixing device shown in FIGS. 8, 9, l and a is a modification of the device shown in FIGS. 1, 2, 3 and 3a and is shown being inserted through softwood 55A into autoclaved aerated concrete 558 by means of a tool 56 which is a modification of the tool punch 16 of FIGS. 1 and 2.

The fixing device shown in FIGS. 8 to 10 and 10a comprises a tubular shank 57 which is formed by rolling metal strip into a semi-circular cross-section or half tube, then folding the half tube double and coldforming the head 58 at the fold and punching a hole 59 in the head 58 to receive a spigot 60 of the tool 56. The shank 57 is thus split longitudinally over the whole of its length except at the head 58 into two half-tubular sections 61 and 62, and has an internal passage 63 open at both ends.

The fixing device shown in FIGS. 8 to 10 and 10a also comprises a pilot member 64 formed as a bit 65 integral with a stem 66. The bit 65 is initially located ahead of the leading end 67 of the shank 57 as shown in FIGS. 8 and 9, whilst the stem 66 is received within the passage 63 and initially gripped loosely between the shank sections 61 and 62. The bit 65 is formed with a forwardly expanding frusto-conical part 68 of which the narrow end merges with the stem 66 and with the, further forward, wider end joined by a forwardly tapering frusto-conical part 69 to a rod-like stub 70 of about the same diameter as the stem 66. The wider end of frustoconical part 68 is the same diameter as the outside of the shank 57 (apart from shank head 58). The function of the stub 70 is to minimise any tendency of the pilot member 64 to wander off course, to one side or another, when it is being hammered in to the softwood 55A and autoclaved aerated concrete 55B (using tool 56). In other words, stub 70 is a direction-stabilizing stub.

The fixing device of FIGS. 8 to 10 and 10a also comprises an annular retainer 71 in the form of a wire ring equivalent in disposition and function to the washer of FIGS. 6, 7 and 7a, that is, to hold the shank sections 61 and 62 together until after commencement of driving the shank 57 through the softwood A into the autoclaved aerated concrete 558, when the ring 71 is moved up the shank 57 by reaction of the softwood 55A in a manner analogous to the washer 50 of the device of FIGS. 6, 7 and 7a.

The spigot of the tool 56' engages the trailing or rear end 72 of the pilot member stem 66 for punching the pilot member 64 directly into the autoclaved aerated concrete 558 in a manner analogous to that described above in respect of the device of FIGS. 1 to 3 and 3a. The tool spigot 60 is mounted in a metal member 73 having a downwardly projecting portion 74 which serves the same purpose as the flange 19 of the tool punch 16 of FIGS. 1 and 2, that is, tool portion 74 limits the depth to which the tool 56 can be used to punch the pilot member 64 as shown in FIG. 9, where the tool portion 74 is shown abutting the surface 75 of the piece of laminated softwood 55A being fixed to the autoclaved aerated concrete 558 by means of the device. The tool 56 also comprises a flexible strap 77, of leather or plastic material, on the member 73.

After the device has been hammered to the depth shown in FIG. 9, (compare FIG. 2,) using a hammer, of which part 78 of the hammer head is shown in FIG. 8, acting upon the tool 56, the tool 56 is removed and the device is hammered home to the position shown in FIGS. 10 and 10a, so that the shank sections 61 and 62 are splayed apart by the pilot member bit part 68, which is gripped by the edges 61a and 62a of shank sections 61 and 62.

As shown in FIGS. 8-10 and 10A, the pilot member stem 66 is sufficiently shorter than the shank 57 so that the rear end 72 of the stem 66 will remain in the shank passage 63 well forward of the shank head 58 after the assembly has been driven into the material 558, whereby the pilot member 64 can be protected by the shank 57 from accidental impact tending to loosen the grip of its shank sections 61, 62 upon pilot member 64.

The fixing systems illustrated in FIGS. 1 to 3 (and 3a) and 8 to 10 (and 10a), particularly FIGS. 8 to 10 (and a), have been found more reliable in use than those of FIGS. 4 to 7. The preferred fixing system is that of FIGS. 8 to 10.

All four devices can be driven through softwood as described hereinabove, forming their own holes. However, metal or other hard members having preformed holes just large enough to accept the devices can be fixed by means of the devices. Furthermore, although the devices are adapted and intended for use in autoclaved aerated concrete and like low density constructional materials, it so happens that the devices will also provide secure fixings in softwood. Indeed, an anchorage in softwood is even more secure because of the resilient frictional grip upon the device, in addition to the positive anchorage provided by the splayed apart shank sections gripping the pilot member.

We claim:

1. A fixing device assembly for being driven already assembled into autoclaved aerated concrete and like low density constructional material, forming its own cavity thereby in said material;

the fixing device assembly comprising:

an elongate shank and a pilot member;

the shank having a leading end and a rear end and comprising:

a plurality of side-by-side part-tubular elongate sections forming in combination a substantially tubular leading end portion of the shank and extending from the leading end towards the rear end of the shank; means integrally, permanently and rigidly interconnecting rear ends of said sections; said sections being separated from each other forwardly of the rear ends of said sections by slits extending continuously from adjacent the rear ends of said sections between side edges of said sections along said leading end portion, said slits opening onto the leading end of the shank;

said sections being adapted to be capable of being flexibly splayed apart from each other forwardly of their rear ends; the shank also comprising a head at its rear end; the shank forming an axial passage extending from the leading end of the shank and between said sections to the rear end of the shank and a tool portion-receiving opening through the head into the passage;

the pilot member comprising a stern received in said passage between said sections of the shank and comprising a bit integral with the stem, said bit being positioned in front of the leading end of the shank; a rear end of the stem being positioned in the shank passage forward of the opening in the shank head; the bit comprising a rearward portion adjoining said stem and a wide part at the front of said rearward portion, said wide part being substantially the same width in cross-section as the external cross-section of the leading end portion of the shank, said rearward portion of the bit tapering rearwardly of said wide part towards said stem;

the pilot member bit being characterised in that it comprises a forward portion adjoining said wide part and tapering forwardly of said wide part towards a narrow leading end of the pilot member bit, whereby the pilot member bit can punch a cavity passage in said constructional material both for the bit itself and for the shank when a tool portion is engaged through the opening in the shank head with the rear end of the pilot member stem and concussive drive is applied thereto, with the pilot member. and shank already assembled together;

the shank being forwardly drivable from an initial position relative to the bit for engagement of the shank sections by said rearward portion of the bit to cause splaying apart of said shank sections, subsequent to the punching of said cavity passage by the pilot member bit;

the shank sections being adapted to individually penetrate the constructional material endwise after being splayed apart, thereby enlarging for themselves the cavity in the constructional material, and to grip the pilot member bit between their side edges;

the pilot member stem being characterised by being sufficiently shorter than the shank so that the rear end of the stem will remain in the shank passage forward of the shank head after the assembly has been driven into the constructional material; whereby the pilot member can be protected by the shank from accidental direct impact tending to loosen the grip by the shank sections on the pilot member after said tool portion has been removed from the shank head opening.

2. A fixing device assembly as claimed in claim 1 and further comprising an annular retainer normally encircling said leading end portion of the shank to initially restrain said sections from splaying outwardly, the annular retainer being movable relatively rearwardly along the shank by engagement with the constructional material as the shank is driven into the constructional material, thereby permitting the splaying apart of said sections of the shank.

3. A fixing device assembly as claimed in claim 2 wherein said annular retainer comprises a washer movable relatively rearwardly along the shank.

4. A fixing device assembly as claimed in claim 1 wherein the narrow leading end of the pilot member bit is defined by a direction-stabilizing stub projecting forwardly from a front end of said forward portion of the bit, the stub being thinner than said wide part of the bit.

5. A fixing device assembly as claimed in claim 1 and further comprising an annular retainer normally encircling said leading end portion of the shank to initially restrain said sections from splaying outwardly, the annular retainer being movable relatively rearwardly along the shank by engagement with the constructional material as the shank is driven into the constructional material, thereby permitting the splaying apart of said sections of the shank, wherein the narrow leading end of the pilot member bit is defined by a directionstabilizing stub projecting forwardly from a front end of said forward portion of the bit, the stub being thinner than said wide part of the bit. 

1. A fixing device assembly for being driven already assembled into autoclaved aerated concrete and like low density constructional material, forming its own cavity thereby in said material; the fixing device assembly comprising: an elongate shank and a pilot member; the shank having a leading end and a rear end and comprising: a plurality of side-by-side part-tubular elongate sections forming in combination a substantially tubular leading end portion of the shank and extending from the leading end towards the rear end of the shank; means integrally, permanently and rigidly interconnecting rear ends of said sections; said sections being separated from each other forwardly of the rear ends of said sections by slits extending continuously from adjacent the rear ends of said sections between side edges of said sections along said leading end portion, said slits opening onto the leading end of the shank; said sections being adapted to be capable of being flexibly splayed apart from each other forwardly of their rear ends; the shank also comprising a head at its rear end; the shank forming an axial passage extending from the leading end of the shank and between said sections to the rear end of the shank and a tool portion-receiving opening through the head into the passage; the pilot member comprising a stem received in said passage between said sections of the shank and comprising a bit integral with the stem, said bit being positioned in front of the leading end of the shank; a rear end of the stem being positioned in the shank passage forward of the opening in the shank head; the bit comprising a rearward portion adjoining said stem and a wide part at the front of said rearward portion, said wide part being substantially the same width in cross-section as the external cross-section of the leading end portion of the shank, said rearward portion of the bit tapering rearwardly of said wide part towards said stem; the pilot member bit being characterised in that it comprises a forward portion adjoining said wide part and tapering forwardly of said wide part towards a narrow leading end of the pilot member bit, whereby the pilot member bit can punch a cavity passage in said constructional material both for the bit itself and for the shank when a tool portion is engaged through the opening in the shank head with the rear end of the pilot member stem and concussive drive is applied thereto, with the pilot member and shank already assembled together; the shank being forwardly drivable from an initial position relative to the bit for engagement of the shank sections by said rearwArd portion of the bit to cause splaying apart of said shank sections, subsequent to the punching of said cavity passage by the pilot member bit; the shank sections being adapted to individually penetrate the constructional material endwise after being splayed apart, thereby enlarging for themselves the cavity in the constructional material, and to grip the pilot member bit between their side edges; the pilot member stem being characterised by being sufficiently shorter than the shank so that the rear end of the stem will remain in the shank passage forward of the shank head after the assembly has been driven into the constructional material; whereby the pilot member can be protected by the shank from accidental direct impact tending to loosen the grip by the shank sections on the pilot member after said tool portion has been removed from the shank head opening.
 2. A fixing device assembly as claimed in claim 1 and further comprising an annular retainer normally encircling said leading end portion of the shank to initially restrain said sections from splaying outwardly, the annular retainer being movable relatively rearwardly along the shank by engagement with the constructional material as the shank is driven into the constructional material, thereby permitting the splaying apart of said sections of the shank.
 3. A fixing device assembly as claimed in claim 2 wherein said annular retainer comprises a washer movable relatively rearwardly along the shank.
 4. A fixing device assembly as claimed in claim 1 wherein the narrow leading end of the pilot member bit is defined by a direction-stabilizing stub projecting forwardly from a front end of said forward portion of the bit, the stub being thinner than said wide part of the bit.
 5. A fixing device assembly as claimed in claim 1 and further comprising an annular retainer normally encircling said leading end portion of the shank to initially restrain said sections from splaying outwardly, the annular retainer being movable relatively rearwardly along the shank by engagement with the constructional material as the shank is driven into the constructional material, thereby permitting the splaying apart of said sections of the shank, wherein the narrow leading end of the pilot member bit is defined by a direction-stabilizing stub projecting forwardly from a front end of said forward portion of the bit, the stub being thinner than said wide part of the bit. 